Tuesday, 29 December 2015

swans and geese

Following up on the "spiders" post last week these shots taken the same day focus on Greater White-fronted Geese and Tundra Swans.

I'd really been hoping to find the local wintering Taiga Bean Geese near Izumo which, though apparently within middendorffii, have slightly different mtDNA and hale from outside the recognised middendorffii breeding range and I gather are morphologically slightly different to the Lake Biwa population.

I find the Lake Biwa birds extremely variable which may simply be down to the inherent individual variation that can be expected within any goose gathering. Not only might I be barking up the wrong tree but there may not even be a tree to bark up. However I'm curious whether Shimane-type Beans also occur at Lake Biwa as it could account for differences I see at Biwako where even setting aside the small number of serrirostris that occur there often seem to be two groups; the obvious swan-like middendorffii and deeper-, shorter-billed birds.

Below is an old digiscoped image which gives an idea of what I mean. I was looking at this flock of middendorffii when the three birds in the foreground dropped in nearby and swam past the flock without joining it. The middendorffii have long bills with a slightly concave culmen and a pronounced bulbous tip. The three geese in the foreground have deeper-based bills with a deeper grin patch and a straight culmen from forehead to tip which almost creates a droop-tipped appearance, quite different to the stand-out middendorffii behind them. As I say there may be nothing more than individual variation in this but it's interesting how often these two types seem to form discrete groups within the flock.  

Three geese which seem to have deeper-based triangular bills (and consequently more prominent grin patches) lacking the bulbous tip extension shown by all the geese in the background.

Getting a good look at the Shimane birds would at least give an idea whether or not the idea might be worth looking into but unfortunately I wasn't able to locate any on the ground and only saw a very distant flock of about 70-80 in flight, identifiable by call. Greater White-fronted Goose was an altogether easier proposition. I saw the first ones roosting on a river at daybreak and small parties were frequent overhead as the sun came up. After locating a few on the ground more began to arrive.

Heads in the grass...

Most of the immatures have a dark nail and some other dark markings along the cutting edge to go with the limited white blaze, others have lost all trace of dark on the nail.

From another angle they weren't quite as in-the-grass as they'd seemed at first.

There were plenty of Tundra Swans around too, this stretch of coast can host large numbers on any suitable fields close to water.

Sunday, 20 December 2015

Billions of spiders... !

I was up on the Japan Sea with my wife for a couple of nights; an eating trip to Tottori city in the main. But I got up one pre-dawn morning to check the fields inland of the coast near Shinjiko.

Freshly fallen snow had been covering the backroads through the mountains on our overnight drive up, my first snow of what has been an exceptionally mild late autumn and early winter. Steep and twisting backroads at night; what was I thinking, of course it would pick then to snow! But milder conditions had returned the morning I spent birding, a hail shower aside there was intermittent light rain and enough of the sun to paint vivid and regular rainbows. An unseasonable small tortoiseshell flitting around riverside berry bushes, presumably looking for non-existant flowers, was a further contradiction to that cautious drive up two nights ago.

Unexpected as the butterfly may have been the biggest surprise was spiders, billions of spiders. I didn't notice them at first, not for a long while in fact, but the tips of emergent vegetation and old stubble alike were festooned with threads. I wasn't parked long before my windscreen was covered with threads and arriving spiders were busy constructing webs on any angle they could find.

So no pictures of the spiders but as any birds feeding over a huge area of fields were draped with fine threads this is all by way to explain their appearance.

Rooks were very common, there were a couple of flocks of over a hundred birds and smaller groups here and there. These flocks were quite mobile but the upside of that was finding any Daurian Jackdaws became far easier than when birds might have been hidden behind field borders. In the end I only found a single Jackdaw and I don't for a moment think I missed any.

Rooks and spider silk...

Daurian Jackdaw...

These Northern Lapwings about a kilometre away didn't fare any better, and notice the streaming spider threads from the stubble...

Eight species of birds of prey weren't getting covered with spider silk. Hen Harrier was the best for me as it's a species I don't often see around Kyoto nowadays but the best photo op came in the form of this approachable Merlin sitting on the wires.

Saturday, 19 December 2015

American Herring Gull (juvenile)

Birding opportunities have all but dried up again over the last couple of weeks due to work; just one more to go before the New Year holidays start. I lieu of getting into the field I thought I'd post a few old images (rather distant and digiscoped) of a bird that hasn't previously appeared on the blog; what seems to be a juvenile American Herring Gull on the Yamatogawa in Osaka November 3rd four years ago.

Like a number of gulls which are rare but occur with reasonable regularity further north in Japan, this would be a mega this far south. In fact there's never been an accepted record in Kansai as far as I'm aware.

The possible confusion taxa for any potential juvenile smithsonianus, are the super-variable Slaty-backed, Vega of course which is much closer in appearance to AHG at this age than it is to argentatus and also Taimyr Gull which may not be the first thing that springs to mind as a potential cause of confusion but it can look surprisingly similar at first glance.

As I said AHG would be a mega here but this gull seems to tick all the boxes, certainly a suite of features look good and there are three important points, the black outer primaries lacking pale inner webs, the dark greater coverts bar and the pale window in the inner primaries, which are wrong for Slaty-backed, Vega and Taimyr respectively.

Slaty-backed is the only one of the trio needing to be eliminated that often presents as structurally different. The SBG on the left has the typical deep-bodied appearance with hanging keel and stout, widely spaced legs. The bird in question is slimmer with a different head shape. The legs are also thinner, less widely spaced and less bubblegum pink. The dark coverts bar is quite prominent at this angle, something Vega doesn't show. 

P8 is exposed here and SBG would show an obvious contrast between dark outer and broadly pale inner webs. Again the dark coverts bar is prominent and might suggest Taimyr but the just visible inner primaries hint at the large pale window on this bird, this would be darker and lack contrast in Taimyr. 

Because I was digiscoping I was unable to get any flight shots and this is one of only two I have to show the spread wing. The window is nevertheless very obvious and contrasts strongly with the almost solidly black outer primaries on the upperwing. The underwing looks very whitish here and could be mistaken for SBG but the latter lacks the heavy dark framing and particularly leading edge. Any juvenile gull can show a whitish underwing in a single image like this. Below are comparative shots of two still fresh juvenile SBG taken in early October this year, one a pale individual the other darker. Though one is much lighter than the other the pattern of both wing surfaces is essentially identical; prominent venetian blinds throughout the outer primaries above and largely whitish below with a narrow, faint trailing edge.  

The only other "flight" shot I have, which though blurry, again shows an obvious window in the upperwing and dark outer primaries below. The general paleness of the underwing continues across the secondaries which are obviously black on the upperwing. Incidentally, the adult behind it is Taimyr (evidenced more by the retained outer primaries than the darker saddle), to its right is Vega and further right still is Slaty-backed.  

At first glance this juvenile Taimyr might recall AHG. It has a heavily saturated shawl, the flanks hint at the possibility of brown uniformity below and the vent / undertail coverts are heavily marked. But once airborne (below) the dark inner primaries give short shrift to that idea (7 Dec 2014).

Again alongside SBG, the head shape looks "Herring group" and the whole appearance is more elegant than the oafish SBG with its short, broad primary projection, drooping skirts and very deep body. The presumed AHG has far less white in the tertial tips than Taimyr, let alone Vega.

I don't have any shots showing the rump, uppertail and tail. In fact the former two were heavily barred and the latter mainly black but that's meaningless as Vega can be equally heavily marked. Again the overall structure is "Herring group"; the head shape looks subtly different to Taimyr with this gull having a long, straight forehead and flattish crown whereas Taimyr tends to have a steeper forehead and more rounded crown.

The vent is heavily barred throughout and the longest undertail coverts almost completely dark but again Vega can match this pattern. However it will not, in my experience, match this greater coverts bar plus I've never seen a Vega with so little white in the tertials.

The clearest image of the vent and undertail coverts.

A Vega in the foreground with slightly greyer, less chocolate underparts and showing far more white in the tertials. This particular bird is already acquiring its next generation mantle and scapular feathers so looks much paler above. Vega doesn't usually look quite as saturated with brown below.

Here with a full juvenile. But juvenile what? At the time I was sure this was Mongolian (and still believe it is) but I didn't confirm it at the time as I was too interested in the other gull. Juvenile Mongolian is very uncommon here, Mongolian is scarce altogether but most juveniles have moulted their mantle and scapulars before they arrive. I wish I'd given this gull a bit more attention.